Buffer State - Europe

Europe

• Kingdom of Hungary, and later Transylvania between the Austrian Empire and Ottoman Empire; see also Banat.
• Poland following World War I, located between Germany and the Soviet Union.
• The Republic of Central Lithuania, existing from 1918 to 1922, was a buffer state between the Second Polish Republic and the Republic of Lithuania.
• Neutral Austria, Sweden and Finland were buffer states during the Cold War.
• Belgium before World War I, serving as a buffer between France, Prussia (after 1871 the German Empire), the United Kingdom and the Kingdom of the Netherlands.
• The Rhineland served as a demilitarised buffer-zone between France and Germany during the inter-war years of the 1920s and early 1930s. There were early French attempts at creating a Rhineland Republic.

The invasion of a buffer state by one of the powers surrounding it will often result in war between the powers. For example, in 1914 the German invasion of Belgium triggered the entry of Britain into World War I.

The earlier forms of highly defended border regions, where defensive castles stood at a distance of a day's march are discussed at Marches. Some political remains of borderland marches established under the Carolingian and Ottonian Empires can be seen on the European map today: Belgium, Luxembourg, Lorraine. The Carolingian Empire also created some independent duchies in the Pyrenean border acting as buffer states against the Muslim kingdoms, an area called the Hispanic March, giving form to today's Andorra, Catalonia, Aragon and Navarre.

Even earlier, compare the highly-defended Roman Empire's limes with its "client kingdoms" like Palmyra, Judaea, Numidia or Mauretania, and the Persian Empire's system of satrapies.